Control mechanism for boilers



Feb. 11;

A. J. FAUCHER CONTROL MECHANISM FOR BOILERS Filed May 12, 1938 2 Sheets-Sheet l Feb. 11, 1941. FAUCHER 2,231,263

CONTROL MECHANISM FOR BOILERS Filed May 12, 1938 2 Sheets-Sheet 2 Andrew cf fez/ch61" Patented Feb. 11, 1941 UNITED STATES PATENT OFFICE 8.0laims.

This invention relates, to new and useful improvements in control'mechanism for boilers. One object of the invention is to provide an improved control mechanism for boilers, which is responsive to changes in boiler pressure, whereby the operation of the boiler is accurately regulated and controlled in accordance with such pressure,which makes itpossible. to maintain a desiredboiler pressure ,andtemperature.

An important object of the invention is to provide an improved control 'mechanismfor boilers wherein a single actuating member is utilized to control the fueland air supplied to the burners, as well as to control the'flue'damper, whereby all of the'adjustable elements which affect the boiler operation are-simultaneouslyadjusted and controlled; the "single actuating member being operated by changes-in conditions within the boiler; whereby the mechanism is' entirely automatic in operation.

Another object-of the invention is to'provide a control mechanism, of the character described, wherein a pivoted masteractuatingmember is employed;'said member being operated by anim- -proved pressure responsive means which isresponsive to pressure changes 'within the boiler, whereby the" member is-automatically swung by i a predetermined pressure-condition.

A further object ofthe invention is to provide an improved boiler control mechanismhaving an actuating memberconnected with and controlling the elements affecting the boiler operation, said member being operatedby a pressure actuatedplunger, which pressure is conducted to the plunger from the boiler; there also being a pilot or control valve interposed between the pressure actuated plunger and the boiler for preventing the application of-pressure -to the plunger until a predetermined pressure is attained, whereby the plunger and actuating mem=- her are operated with a smooth and even action.

A construction designed to carry out the invention will be hereinafter described, together with other features of the invention.

5 The invention will be more readily understood from a reading of the following specification and .by reference to the accompanying drawings, in which an example of the invention is shown, and

wherein:

Figure 1 isan isometric View of a boiler having a control mechanism, constructed in accordance with the invention, attached thereto,

Figure -2.. is a View partly in elevation and partly in section .of the operating diaphragm iandhits associate-parts,

able damper I9 is mountedwithin the flue.

damper is secured toa shaftl9 which has one 45 end projecting through the -flue. This projecting "Figure 31s a plan view ofthe parts shown in Figure 2,

f Figure '4' is a horizotnal, cross-sectional view taken on the line 4-4 of Eigure'2,

Figure 5, is an elevation of, the master, control 5 bar and having portions thereof. broken away to more clearly illustrate; the invention,

Figurefi is a. transverse, vertical,- sectional view .taken on theline. 6"6 of Figure 5,

taken'ion the line"9-+9"of Figured; and

Figure 10 isa transverse, -vertical, sectional "view taken through the "bleeder header.

Inthe drawings,:the-'numera1 l0 designatesa' 20 boiler which'may beof any desired construction. "The boilerhas the usual burners (not shown) therein and fuel is "supplied; to .said burnersthrough a fuel supply -line H- which extends through the front-or end wall of the boiler boils-= ing. -A suitablecontrol valve i2 is connected in the line H and has a pivoted control arm l3 -which is arranged to open enclose the valve to control the flow of fuelto the burners.

The usual air inlet louvers or'doors M which con- 30 -trol admittance of fresh air-to the combustion chamber are located in the end wall of the housing, being hinged'to swing on rods P5 in the usual manner. The end of the rod Iii-of each door is extended and *has an arm 18 secured35 thereto and the arms are connected by-a link I 1, whereby said armsareswung simultaneously. Manifestly,-when the arms it are swung the-rods -'|5arerota-ted to swing the louversor doors I4, -whereby more or less air isadmitted to the-com- 40 bustion chamber.

The boiler-casingor housing has theusual flue i8 -extending upwardly therefrom and a suit- The end of the shaft is provided with an-actuating As is wellknown, it is desirable in --operating *a boiler that when the fuel supply-is varied; the air supply through the 'louvers l4,-as well as the 55 position of the damper I9, be varied accordingly.

Similarly, a change in the air supply or a variation in the position of the damper requires a change in fuel supply. Thus, in order to efficiently control the boiler, the fuel control valve I2, the louvers I4 and the damper I9 must be operated simultaneously in order that their relative positions to each other be maintained under all operating conditions.

For accomplishing the simultaneous operation of theseelements, a master control bar 22 is pivotally mounted at one side on the boiler II]. This bar has one end overlying a block 23 which block is formed with ears 24 at one end. Tie bolts 25 extend upwardly through the block-on each side of the bar and pass through a transverse retaining plate 25 which engages the top of the bar. The bolts receive-nuts 21 and manifestly, said bolts and plate fasten the bar and block together.

The inner face of each ear 2d of the block is formed with a vertical recess 28 which recess has its lower end rounded, whereby an annular bearing element or ring 29 is insertable therein. An upstanding lug 30 is disposed between the cars 24 and a transverse shaft 3i is supported in said lug, the ends of said shaft being insertable within the bearing rings 29. The bottom of the shaft is sharpened to a knife edge (Figures 2 and 5) and this edge rests on the inner periphery of the rings at the lower portion thereof, as will be explained.

The supporting lug 39 is formed integral with a collar 32 which encircles the upper end of a tubular sleeve or cylinder 33. The cylinder extends upwardly from a diaphragm case 34. As is clearly shown in Figure 2, the lug 39 overhangs the upper end of the cylinder so as to be sup- -to said cylinder by a set screw 35.

ported thereby and the collar 32 may be fastened A lateral arm 36 is preferably madeintegral with the collar and extends beneath the block 23 and bar 22. An adjustable bolt 31 is threaded through underside of the block to limit the downward swinging of the block and bar. An angular bolt 38 extends through the arm 36, being adjustably retained by nuts. 38', and has its lateral extension overlying the top of the block for limiting upward swinging of the block and bar.

, From the foregoing, it is obvious that the block 23 which has the actuating bar 22 secured thereto is pivotally mounted on the shaft 3| and when the block is swung, said bar is also swung. For imparting movement to the block, a plunger 39 is disposed within the cylinder 33 and the lower end of the plunger rests upon a pressure responsive diaphragm 49 suitably clamped within the case 34. The upper end of the plunger has a replaceable bearing cap M mounted thereon and said cap has an upstanding transverse fin 42 formed with a knife'edge. The fin engages within a recess d3 provided in the underside of a bearing plate 44 which is fastened to the underside of the block 23. The actuating bar 22 and block 23 are held in a lowered position, so that the plate 44 and fin 42 are in constant engagement, by a weight 45 which is adjustably mounted on the free end of the bar 22. With this arrangement the weight 45 is constantly pulling the free end of the bar 22 downwardly with the result that the knife-edge fin 42 forms a fulcrum point, thereby swinging the pivoted end of the arm upwardly so .that the knife edge of the shaft 3I is held in constant engagement with the inner periphery of the bearing rings 29. The knifeedge bearing contacts or points reduce frictional Wear in the mechanism and make the same more sensitive in operation.

The bottom of the diaphragm case 34 has a short pipe 46 connected therein and a T 41 is connected to the lower end of said pipe. A vertical standard 48 which extends upwardly from the floor, or other support, has its upper end fastened into the T and supports the diaphragm case 34, cylinder 33 and their associate parts including the actuating bar. The lateral outlet of the T 4! has a pressure line 49 threaded thereinto and said line conducts pressure through the pipe 46 into the case below the diaphragm 49.

When the pressure acting against the diaphragm is suificient to overcome the weight 45 on the arm 22, the plunger 39 moves upwardly to swing said arm on the shaft 3|. As soon as the pressure below the diaphragm drops, the weight returns the bar 22 to its lowered position. The

swinging movement, which the bar may undergo, may be readily varied by adjusting the limiting bolts 33 and 31 which are adapted to engage the top and bottom of the block 23 secured to the bar.

In order to operate the damper I9 when the I bar 22 is swung, a chain, or other flexible connection 59 has one end secured to a collar 5I slidably fastened on thearm. The chain passes over a pulley 52 mounted on the side of the boiler housing and has its other end fastened to the control arm 29 of said damper. When the bar 22 is swung, it is evident that the damper arm 29 is also swung through the medium of the chain 59. To vary the movement imparted to the arm 29 by the swinging of the bar 22, it is possible to move the collar 5|, to which the chain is secured, along the bar 22, whereby its position to the pivot point 3| is varied, with a resultant variation in stroke or movement imparted to the chain.

For actuating the fuel control valve I2 and the air supply louvers I4 at the same time that the damper I9 is adjusted by the swinging of the bar 22, a second actuating bar 53 is provided.

This bar is pivoted to a bracket 54 which is secured to the upper end of the pipe 45 and is connected to the master-bar 22 by a link 55. As is clearly shown in Figure 1, the link is adjustably secured to the bars'so that it may be secured thereto at various points therealong, whereby the stroke or swinging movement of the bar 53 may be readily varied. A chain, or other flexible connection, 56 has one end adjustably secured to the outer end of the arm 53 and said chain passes over pulleys 57 which are mounted on the boiler housing. The other end of the chain is secured to an arm 53 which is fastened -on a shaft 59 rotatably mounted in brackets 69. The shaft has a radial arm 62 which is connected by a chain, or other flexible connection, 63 with the control arms I6 of the louvers. A second radial arm 64 is secured to the shaft and has connection through a chain 35, which passes over adjusts the damper I9 through the chain 50 and at the same time moves the bar 53' which adjusts I ing of the bar will reduce the fuel supply and will the' boiler operation.

the lo'uvers I l-and valve l 2-by rotating the shaft 159 through the medium of the chain'56. lTherefore, all three elementspthe'valve I2, l ouvers l4 .and damper I 9, are simultaneously adjusted to efiicie-ntly control the operation of theboiler.

The-pressure which operates the diaphragm 40 may .be conducted to the lateral pressure line 49 from any suitablesource, but. it is preferable that the boiler p-ressure be utilized'to operate the diaphragm. By using the boiler pressure to control the diaphragm, which, in turn, controls the bar I 22, it will beseen that the variouselements which effect the operation of the boiler are automatically controlled in accordance with the boiler conditions. The pressure from within the boiler may be conducted therefrom by a pressure line or pipe 'lfl which has one end connected in the top of theboiler housing. The other end of the line it may; if desired, be connected with the 1ine49 "whereby the boiler" pressure is conducted directly to the diaphragmdll. If this hook up is used, the -weight 45 on the free orouter end of the bar 22 is properly adjusted so that when'a predetermined pressure is attained within the boiler, the diaphragm 4!] is lifted to swing the bar 22. Swingalso adjust the air supply louvers I4 and the damper l9, whereby the boiler output is cut down.

Whenever the pressure within the boiler drops below a predetermined point, as determined by the adjustment of the weight 45, the bar 22 is returned to its original or-lowered position, whereby thevalvel2, louvers l4-and damper-l9 are adjusted to step up or increase the boiler output. In this manner, a predetermined or fixed pressuremay be automatically maintained at all times within the boiler.

Although itis p0ssible,-as has been explained,

" to connect the line ll] directly with the pressure linedQ -so'that the pressure from the boiler is conducted directly to the diaphragm 40, it is not particularly desirable.

This is true "because the pressure will build up slowly below the diaphragm -40 and-will gradually move said diaphragm upwardly; whereby the bar 22 is gradually swung to "anupward position, which results in a gradual adjustment of the various elements which affect It ispreferable that the diaphragm lee-moved upwardly immediately so as to swing the bar ina continuous motion froma loweredto a raised position.

To accomplish this operation of the diaphragm 82 at its upper end. A diaphragm l3 overlies the a secondflange which is formed at the base of a vertically extending cage 75. A coil spring '66- has its lower end resting on the upper surface of the diaphragm13, while the upper end of the coil spring is engaged by an adjusting screw 11 which is threaded to the-top of the cage. By adjusting the screw ll, it is manifest that the tension on the spring may be varied and since said spring is exerting its pressure against the dia- 'phragm, it is manifest that the amount of pressure necessary to raise said diaphragm may be 'varied by adjusting said screw.

axial stem 18 depends from the diaphragm F13, extending through the "bore of thebody- I l -said body beneath the diaphragm 13.

the diaphragm is in a lowered position, being held so by the spring 16, whereby the valve. pin 19 car- .ried by the diaphragm stem 18 is in a seated po- (1 sition. Therefore, the pressure entering the bore valve 18.

within the line 70 andbore of the body 'il may flow through the port sfl, line 84, T85, line 49-and and the lower end of" said 'stem carries-a conical -valve-member or pin 19. "The pin His-adapted to close a port 80 which is formed within aflow bean fll --mounted within-the bore--82of a block 83; The block-83 vflangedat its upper end and fastened to a flange formed'at the lower end -of-the body 7 I the bore 82- of--the blockanda T 85 is connected withsaid line. The lateral pressure line which An-outlet line 84 is connected in leads 'fronr the T- 4'! below the diaphragm 40 has itsopposite end connectedv in the T 85 whereby when the-valve pin ll is unseated, communication between the bore of the body "It and the diaphragm case 34,. is established.

The pressure line IO-from the interior of the boiler l has its other end connected in-a radial port 86 whichis formed in the body H, whereby the boiler pressure is conducted into the bore of Normally,

of the body 'H through the line 10 is trapped withinsaid bore and acts against the diaphragm 13. As soon as this pressure overcomes the pressure of the spring T8, the diaphragm 13 moves upwardly toraise the stem 18 and unseat the As soon as this occurs the pressure finally through the .pipe dii into the diaphragm case 34 below the diaphragm 4B. The-adjustment of the spring 16 is-such that the valve pin [9 is unseated only whensufficient pressure has been built up to actuatethe diaphragm 40 to move thesame to its upper position. Therefore,

as soon as the valve pin 19 opens the port, the

pressure is directed against the diaphragm 40 and the master bar 22 is immediately swung to its raised position.

When the pressure within the boiler-l0 falls below a predetermined point, the diaphragm 40 -moves downwardly to return the master bar 22 to its lowered position. The pressure drop Within the bore of the body H permits the diaphragm "F3 to be moved downwardly by the springit, where- .by the valve pin-19 is again seated to close the port 80 and out off communication between the body H and the diaphragm case 34. Any presi -sure which might be trapped between'the diaphragm 4D and the valve pin 19, which is within the line 49, may escape through a bleeder 81 which is connected in the latter line. This bleeder comprises a tubular header 88 having-a bean 89 in its lower end. The bean is provided with a re- :duced port 90 which communicates with the bore of the header, whereby pressure within the line 49 may escape upwardly into said bore. A radial port 9i is formed in the upper end of the header and-le-ads from the bore thereof and a suitable discharge pipe 92 may be screwed into the bore '9! to conduct the pressure from the bore of the header. It is pointed out that the size of the port 9|] is sufficiently small so that very little pressure can escape therethrough. Therefore, when the pressure is operating the diaphragm, the small amount of pressure through the bleeder port 90 I does not affect the normal operation of the device.

It has been'found that the various parts of the pilot A may corrode and must be cleansed by means of a suitable chemical, or other substance.

In order to keep the valve pin 19 and itsassociate ='-parts clean, -a suitable cleaning substance may he introduced into the'b'ore of the body'- H through W5 j acond'uctor 93. A control valve 94is mounted in the conductor and above said valve a container 95 for holding the cleaning substance, is located. When the valve 94 isopened, the substance flows downwardly through the pipe 93 and into the bore of the body H, whereby it contacts the valve pin and its associate parts. The cleaning substance may be drained fromthe bore of the body H through an angular outlet port 96 which has a suitable pet cock or valve 9'! at its outer end.

From the foregoing, it will be seen that the pilot A provides a means whereby a predetermined pressure must be built up within the boiler l0 and the line Ill, before such pressure is conducted to the diaphragm Ml which operates the master bar 22. A'suitable hand valve 98 may be connected in the pressure line H3 in advance of the pilot A, whereby the flow of pressure through this line may be readily controlled. Also, if desired, a strainer 99 may be mounted in the line H1 so as to prevent foreign matter from entering the pilot A. Although it is desirable to employ the pilot, it is again pointed out that said pilot may be eliminated, in which case the line 10 will be connected directly with the pressure line 49 leading to the diaphragm 49.

What I claim and desire to secure by Letters Patent, is:

l. A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivoted to a support at one side o the boiler, means slidably mounted on the bar and movable to various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for adjustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these elements at any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the lever actuates the valve and control, and pressure responsive means for swinging the master control bar to actuate the damper and also to swing the lever to operate the fuel valve and air control.

2. A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivoted to a support at one side of the boiler, means slidably mounted on the bar and movable to various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for adjustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these elements at any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the .lever actuates the valve and control, pressure responsive means for swinging the master control bar .to actuate the damper and also to swing the lever to operate the fuel valve and air control, a conductor leading from the boiler to the pressure responsive means for conducting a. pressure to said means, whereby the pressure responsive means is operated in accordance with the pressure in the boiler.

3. A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivoted to a support at one side of the boiler, means slidably mounted on the bar and movable to various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for adjustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these elements at any point thereon with respect to their pivots, a collar slidably mounted on the control lever and movable to any position thereon with respect to the pivot point of said lever, said collar being arranged to be locked in its various adjusted positions, a flexible connection having one end secured to the collar with its other end operatively connected to the fuel supply valve and air supply control, whereby swinging of the lever actuates the valve and control, and pressure responsive means associated with the master control bar for swinging the same I to actuate the damper and also to swing the lever and operate the fuel valve and air control.

4. A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivoted to a support at one side of the boiler, means slidably mounted on the bar and movable to various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for adjustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these elements at any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the lever actuates the valve and control, a cylinder disposed below the master control bar and having a pressure responsive element in its lower end, a plunger of smaller diameter than the cylinder mounted in said cylinder above the pressure responsive element, said piston having a point contact with the underside of the control bar, a weight adjustably mounted on the outer end of the bar for holding the bar in contact with the piston, and means for conducting a pressure to the underside of the pressure re-,

sponsive element to xmove the. piston upwardly and thereby swingthecontrol bar to actuate the damperanol tov swing the control lever and thereby. operate the. fuel valve and air control.

5. A control mechanism for a boiler having a fuel supply valve, an air supply. controland a flue damper including, amaster control bar, having one end pivoted to-a,support at one side of the boiler, means slidablymounted on the bar andmovable to various positions thereon so as to change its location relative to the pivot point otthe bar, said means being arrangedto be locked in any of its adjusted positions, a flexible connection between said means and'the damper of the boiler, wherebyswinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for a djustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these elements at any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the lever actuates the valve and control, a cylinder disposed below the master control bar and having a pressure responsive element in its lower end, a plunger of smaller diameter than the cylinder mounted in said cylinder above the pressure responsive element, said piston having a point contact with the underside of the control bar, a weight adjustably mounted on the outer end of the bar for holding the bar in contact with the piston, a conductor leading from the boiler'to the pressure responsive element for conducting a pressure to said element whereby the element and piston are actuated in accordance with the boiler pressure, and a valve interposed between the boiler and pressure responsive element for controlling the pressure passing to said means.

6. A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivoted to a support at one side of the boiler, means slidably mounted on the bar and movable to various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for adjustably connecting the ends of the link to the bar and lever, whereby said link. may be connected to these elements at any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the lever actuates the valve and control, a cylinder disposed below the master control bar and having a pressure responsive element in its lower end, a plunger of smaller diameter than the cylinder mounted in said cylinder above the pressure responsive element, said piston having a point contact with the underside of the control bar, a weight adjustably mounted on the outer end of the bar for holding the bar in contact with the piston, a, conductor leading. from i the boiler to the pressure responsive element for conducting a pressure to said element whereby theelement and piston are. actuated in accordance with the boiler pressure, a valve interposed between the boiler and pressure responsive element for controlling the pressure passing to said means, and pressure actuated means for controlling the position of the valve,

wherebya predetermined pressure must be bulit up in the boiler before said pressure is conducted to the pressure responsive element;

'7; A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivotedJto-asupport at one side of the boiler, means sli'dablymounted on the bar and movable to. various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master control bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever, means for adjustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these elements at any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the lever actuates the valve and control, a cylinder disposed below the master control bar and having a pressure responsive element in its lower end, a plunger of smaller diameter than the cylinder mounted in said cylinder above the pressure responsive element, said piston having a point contact with the underside of the control bar, a weight adjustably mounted on the outer end of the bar for holding the bar in contact with the piston, a conductor leading from the boiler to the pressure responsive element for conducting a pressure to said element whereby the element and piston are actuated in accordance with the boiler pressure, a tubular housing connected in the conductor between the boiler and said means, a valve seat at the lower end of the housing, a plunger valve movable within the housing and adapted toengage the seat, and a diaphragm at the upper end of the housing and connected with the plunger valve, said diaphragm being constantly exposed to the boiler pressure whereby said pressure acting thereagainst raises the valve to admit the pressure through the conductor to the pressure responsive element.

8. A control mechanism for a boiler having a fuel supply valve, an air supply control and a flue damper including, a master control bar, having one end pivoted to a support at one side of the boiler, means slidably mounted on the bar and movable to various positions thereon so as to change its location relative to the pivot point of the bar, said means being arranged to be locked in any of its adjusted positions, a flexible connection between said means and the damper of the boiler, whereby swinging of the bar adjusts said damper, a secondary control lever having one end pivoted to a support and spaced from the master contro1 bar, a connecting link between the control bar and lever so that swinging of the bar results in a swinging of the lever,

means for adjustably connecting the ends of the link to the bar and lever, whereby said link may be connected to these element'sat any point thereon with respect to their pivots, flexible connecting means between the secondary lever and the fuel supply valve and the air supply control, whereby swinging of the lever actuatesthe valve and control, a cylinder disposed below the master control bar and having a pressure responsive element in its lower end, a plunger of smaller diameter than the cylinder mounted in said cylinder above the pressure responsive element, said piston having a point contact with the underside of the control bar, a weight ad'justably mounted on the outer end of the bar for holding the bar in contact with the piston, a conductor leading from the boiler to the pressure responsive element for conducting a pressure to said element whereby the element and piston are actuated in accordance with the boiler pressure, a tubular housing connected in the conductor between the boiler and said means, a valve seat at the lower end of therhousing, a plunger valve movable within the housing and adapted to engage the seat, a diaphragm at the upper end of the housing and connected with the plunger valve, said diaphragm being constantly exposed to the boiler pressure whereby said pressure acting thereagainst raises the valve to admit the pressure through the conductor to the pressure responsive means, and a coiled spring above the diaphragm for urging the same downwardly against the boiler pressure, whereby a predetermined pressure must be present to lift the valve and admit pressure to said pressure responsive means.

ANDREW J. FAUCHER. 

